Fast focus for baby shots


whelmed

Link Posted 13/04/2012 - 21:53
So what's the fastest focusing lens in the 18-50mm range. Can be a prime or a zoom. My experience with SDM is that it's wonderful IQ but focusing is slow as crap. I've had a 16-50mm DA*, 18-50mm f2.8 siggy, 30mm f1.4 siggy (non HSM), 50mm FA 1.4, 35mm DA 2.4, and I'm sure I'm missing one more in that range.

So what focuses faster than those lenses (if anything?). If a 31mm LTD does I'll shell out for it, but I want something that lets me get close to my subject (my baby girl) and that focuses really fast.

Thanks!
K-5; Siggy 10-20 f4, 30mm f1.4, 18-50mm f2.8, 70-200mm f2.8; Tammy 400mm f4, 500mm f8

ChrisA

Link Posted 13/04/2012 - 22:01
The 18-135 is the fastest focusing Pentax lens that I've encountered, by a significant margin.

The 35mm DA 2.4 is hardly slow, and neither is the 50mm FA 1.4. The 17-70 is fairly fast, I find, despite being SDM.

None of these is as quick as the 18-135.

If it's not fast enough, you need to fix your technique, or change to Nikon
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Pentax K-3, DA18-135, DA35 F2.4, DA17-70, DA55-300, FA28-200, A50 F1.7, A100 F4 Macro, A400 F5.6, Sigma 10-20 EXDC, 50-500 F4.5-6.3 APO DG OS Samsung flash SEF-54PZF(x2)
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Last Edited by ChrisA on 13/04/2012 - 22:05

JamieT

Link Posted 13/04/2012 - 22:03
I would work the other way round and slow her down....brandy on the dummy?
K5, LTD 15 SIG 30, SIG 105.

JAK

Link Posted 13/04/2012 - 22:07
The fastest focussing lenses are the SDM ones. SDM is nothing to do with IQ, it stands for 'Supersonic Drive Motor.'

Have you tried the DA 17-70? That focusses pretty quickly on a K-5 and is SDM.

All lenses will struggle in low light situations though but I'm surprised you had a problem with the f1.4 ones.

A suggestion, have you tried using a different focussing mode? I find using the 'centre' setting works well and allows me to get the point that I want to be in focus rather than have the camera decide for me what it thinks I want!

John
John K

Mike-P

Link Posted 13/04/2012 - 22:17
JAK wrote:
The fastest focussing lenses are the SDM ones. SDM is nothing to do with IQ, it stands for 'Supersonic Drive Motor.'


The fastest focusing lenses are the ones with the shortest focus throw.

The SDM lenses are actually mostly slower than screw drive .. the 16-50mm, 50-135mm, 60-250mm and 55mm are particularly bad .. the 300mm isn't much better.

The 18-135mm is fast .. as is the DA 40mm.

Edit: forgot to include the glacial 50-135mm.
No equipment list here but thanks for taking an interest. My Flickr
Last Edited by Mike-P on 13/04/2012 - 22:45

ChrisA

Link Posted 13/04/2012 - 22:21
Mike-P wrote:
The SDM lenses are actually mostly slower than screw drive .. the 16-50mm, 60-250mm and 55mm are particularly bad .. the 300mm isn't much better.

The 18-135mm is fast .. as is the DA 40mm.

18-135 is DC, not SDM, as Gwyn, I think, pointed out to me when I made the same mistake.

The other thing is, a lot is made of the lenses that have a longer focus throw, and all other things being equal, they are slower, as Mike says.

The 55-300 is often cited as a slow one in that regard. However, that assumes it needs to go from infinity to close up, which it rarely does. Get it close to where it needs to be, and it's quite quick.
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Pentax K-3, DA18-135, DA35 F2.4, DA17-70, DA55-300, FA28-200, A50 F1.7, A100 F4 Macro, A400 F5.6, Sigma 10-20 EXDC, 50-500 F4.5-6.3 APO DG OS Samsung flash SEF-54PZF(x2)
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whelmed

Link Posted 13/04/2012 - 22:22
Maybe it's my comparison point - I used a friends D700 with a 24-70mm f2.8 it it was like it thought for me. Push down and wham, perfect. Same with another friends Canon 60D who had the 24-70mm L series, which I found an interesting FL on a crop body, but same result. The DA* I had with SDM would take forever and hunt back and fourth before locking on in lowish light. I didn't try to FA 50mm on my K-5, I've had 2 - one ages ago which I sold because of lack of use, then I rebought and this tine never took it out of the box so I sold it again. Also 50mm is a touch too long on crop frame for me. I've started using the 35mm f2.4 a touch lately and will see if it does it for me or not, but I very much feel the loss of the (almost) 2 stops over the Sigma 30mm f1.4 and not much more in terms of speed.

Perhaps I need to just start shooting with a dampened flash at F/8 to give me a little 'wiggle' room? Would the sigma HSM be any faster, or the 31mm LTD?
K-5; Siggy 10-20 f4, 30mm f1.4, 18-50mm f2.8, 70-200mm f2.8; Tammy 400mm f4, 500mm f8

ChrisA

Link Posted 13/04/2012 - 22:25
whelmed wrote:
Maybe it's my comparison point - I used a friends D700 with a 24-70mm f2.8 it it was like it thought for me. Push down and wham, perfect. Same with another friends Canon 60D who had the 24-70mm L series,

You're hardly comparing like with like

If lightning fast AF is your main requirement, you'll need to spend money, lots of it, and not on Pentax.
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Pentax K-3, DA18-135, DA35 F2.4, DA17-70, DA55-300, FA28-200, A50 F1.7, A100 F4 Macro, A400 F5.6, Sigma 10-20 EXDC, 50-500 F4.5-6.3 APO DG OS Samsung flash SEF-54PZF(x2)
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Last Edited by ChrisA on 13/04/2012 - 22:26

whelmed

Link Posted 13/04/2012 - 22:29
The only problem is that to upgrade to a FF / top end glass in canikon is that it's serious serious cash. Basically, I've got 500-600GBP burning a hole in my pocket at and I'd like to get something part way there If I had 3000-4000 then I'd ponder Canikon.
K-5; Siggy 10-20 f4, 30mm f1.4, 18-50mm f2.8, 70-200mm f2.8; Tammy 400mm f4, 500mm f8

Mike-P

Link Posted 13/04/2012 - 22:33
If I want focus speed I use my 50D now.

Pentax have got better with the K-5 but it's still no match for even one of Canons 4/5 year old bodies.
No equipment list here but thanks for taking an interest. My Flickr

ChrisA

Link Posted 13/04/2012 - 22:34
whelmed wrote:
The only problem is that to upgrade to a FF / top end glass in canikon is that it's serious serious cash. Basically, I've got 500-600GBP burning a hole in my pocket at and I'd like to get something part way there If I had 3000-4000 then I'd ponder Canikon.

Well I'd say that the 18-135 on the K-5 is a reasonable chunk of 'part way there'.

Rent one from SRS, see how you get on. Or buy one. You'd get back something close to what you paid, less the cost of the rental if you decided you didn't like it.

If you decide to go down that road, have a poke about on here for reviews of the lens. It's fast focusing, compact, light, in fact a delight in every way except that at anything longer than about 50mm it's not great away from the centre.

But a baby will mostly be in the centre, and you say you want the shorter end of the range. So it might be just about the right compromise for you.
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Pentax K-3, DA18-135, DA35 F2.4, DA17-70, DA55-300, FA28-200, A50 F1.7, A100 F4 Macro, A400 F5.6, Sigma 10-20 EXDC, 50-500 F4.5-6.3 APO DG OS Samsung flash SEF-54PZF(x2)
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Last Edited by ChrisA on 13/04/2012 - 22:35

Smeggypants

Link Posted 13/04/2012 - 22:37
JamieT wrote:
I would work the other way round and slow her down....brandy on the dummy?

Yeah! big can of freezer spray!!!
[i]Bodies: 1x K-5IIs, 2x K-5, Sony TX-5, Nokia 808
Lenses: Pentax DA 10-17mm ED(IF) Fish Eye, Pentax DA 14mm f/2.8, Sigma 17-70mm f/2.8, Pentax-A 28mm f/2.8, Sigma 30mm F1.4 EX DC, Pentax-A 50mm f/1.2, Pentax-A 50mm f/1.4, Pentax-FA 50mm f/1.4, Pentax-A 50mm f/1.7, Pentax DA* 50-135mm f/2.8, Sigma 135-400mm APO DG, and more ..
Flash: AF-540FGZ, Vivitar 283

Smeggypants

Link Posted 13/04/2012 - 22:38
Mike-P wrote:
If I want focus speed I use my 50D now.

Pentax have got better with the K-5 but it's still no match for even one of Canons 4/5 year old bodies.

Yup, truth might hurt for the "Pentax can do no wrong!" Sycophants though.

I'm still not buying a Canon though.
[i]Bodies: 1x K-5IIs, 2x K-5, Sony TX-5, Nokia 808
Lenses: Pentax DA 10-17mm ED(IF) Fish Eye, Pentax DA 14mm f/2.8, Sigma 17-70mm f/2.8, Pentax-A 28mm f/2.8, Sigma 30mm F1.4 EX DC, Pentax-A 50mm f/1.2, Pentax-A 50mm f/1.4, Pentax-FA 50mm f/1.4, Pentax-A 50mm f/1.7, Pentax DA* 50-135mm f/2.8, Sigma 135-400mm APO DG, and more ..
Flash: AF-540FGZ, Vivitar 283

Smeggypants

Link Posted 13/04/2012 - 22:41
JAK wrote:
The fastest focussing lenses are the SDM ones.
John

No they are not sadly. Quite the opposite in fact.
[i]Bodies: 1x K-5IIs, 2x K-5, Sony TX-5, Nokia 808
Lenses: Pentax DA 10-17mm ED(IF) Fish Eye, Pentax DA 14mm f/2.8, Sigma 17-70mm f/2.8, Pentax-A 28mm f/2.8, Sigma 30mm F1.4 EX DC, Pentax-A 50mm f/1.2, Pentax-A 50mm f/1.4, Pentax-FA 50mm f/1.4, Pentax-A 50mm f/1.7, Pentax DA* 50-135mm f/2.8, Sigma 135-400mm APO DG, and more ..
Flash: AF-540FGZ, Vivitar 283

whelmed

Link Posted 13/04/2012 - 22:46
Re the 18-135mm, there was a fairly recent review (last 6-12 months) that made me cringe so I am quite gun-shy on it. It was from a respectable site as well, though the name escapes me right now.

The IQ on the K-5 is on par with most of the Canikon FF bodies I've seen, with the obvious problem being that it's crop so you loose the DOF. I'd take it, IQ wise, over a 5D mk II for instance. Just trying to track my spazmo of a child (who is now 4.5 months old and I hope never reads this) gets tough, and to pull off a low DOF shot prior to her moving out of the sweet zone is near impossible without shotgun mode (taking 20 shots and hoping she moves back to the sweet spot). Only problem is that she normally is not smiling anymore, has puked, is about to sneeze, has her hand in her mouth, etc. by the time she has moved back to where my focus lock was initially. Yes, she is my little spaz of a child.

Hmm... So may have to take my camera to a store and just try some sample shots with a 18-135 and see if it is as bad as they talk about in the review.
K-5; Siggy 10-20 f4, 30mm f1.4, 18-50mm f2.8, 70-200mm f2.8; Tammy 400mm f4, 500mm f8
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